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UNIVERSAL STAIR CLIMBLING
EXPLORER (USCE 1.0)
Balakumaran.R [1], Aravind.R.R[2]
[1] Mechanical Department, final year, Dhirajlal Gandhi College of Technology, Salem, Tamil Nadu.
[2] Mechanical Department, final year, Dhirajlal Gandhi College of Technology, Salem, Tamil Nadu. Ph.no: 7502123823 [1], 8760938554 [2],
Mail Id: [email protected] [1], [email protected] [2]
Abstract - In the present scenario the
application of robots is quite common to reduce
the human effort in several areas. The stair
climbing robots are used to climb the stairs for
different applications up to now, but the main
disadvantage of the rugged terrain robots is not
adjustable according to the structure of the stairs.
To overcome this, we have developed a stair
climbing robot to climb the stairs up and down
according to the dimensions of the staircase by
using standard step ratio (i.e.,) rise=7.5inch, run
=11inch, angle = 30-36 degree. The main
features of the robot include the mechanical
gears components which is attached to the body
frame to lift the materials up and down as per the
motor capacity. This paper presents the design
and implementation of a feedback control system
for a remote-controlled stair climbing robot. The
robot is controlled using Arduino. . The operator
can monitor the scenario by using video that are
captured through a camera on the surface of the
robot. Experimental trials showed that the
implementation of the behavior control systems
was successful.
I. INTRODUCTION
Robots are increasingly being integrated
into working tasks to replace humans. They are
currently used in many fields of applications
including office, military tasks, hospital operations,
industrial automation, security systems, dangerous environment and agriculture [1].Several types of
mobile robots with different dimensions are
designed [2-8] for various robotic applications. The
robot has been designed for the purpose of aiding
rescue workers. A stair climbing robot is one of the
most attractive performances of robot in legged and
wheeled. Developments have been made on various
kinds of stair climbers, considering how to make its
climbing ability higher and its mechanical
complexity reasonable and practical. The research
includes realizing a large step negotiating. Reducing body weight and energy consumption is
also the important matter of developing. We use a
standard step ratio of stairs, to make our robot to
climb any universal steps. The standard step ratio is
nothing but the height, length and angle of the
stairs. The length of the stairs is called as rise, and the height of the stairs is called as run. The
standard size of the stairs are rise=7.5inch,
run=11inch and angle=30-36 degree. A machine is
a collection of mechanisms which transmits force
from the source of power to the load to be
overcome, and thus perform useful mechanical
work. Robotics is the area of automation which
integrates the technology in variegated fields like
mechanisms, sensors & electronic control systems.
2. OBJECTIVES
After discussing amongst our group, and the following objectives were established at the
beginning of the project.
1) To design and manufacture a stair-climber
which can climb up and down and also
move in left and right direction.
2) To simplify the complex driving
mechanisms into a simple mechanisms and develop an Arduino program to
control the movement of the wheel.
3) To maintain simplicity of our design
throughout the project.
3.0 TECHNICAL REQUIREMENTS
AND CONSIDERATION
The size of the robot must fit those of the stairs;
1) It will not be too large to be
accommodated by each step of the stairs.
2) The width of the robot must be well-
defined within a suitable range such that it
is zygomorphic for body balance on both
sides. This can be achieved by a
symmetric design and positioning of components.
3) Since the stair-climber will be lifted up to
climb the stairs, its weight to be supported
must not be too large such that it will not
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burden or exhaust the weight supporter,
which most probably, is the motor.
4) Components must be concisely designed
and manufactured with proper materials.
The center of mass is arranged at the front
side of the climber (the side ahead when
going upstairs) such that it can facilitate
the actions of climbing upstairs and
prevent the robot from toppling and
flipping over when going downstairs.
5) The method of controlling the robot must
be well-considered. If a manual approach
is employed, the user must be trained to familiarize with the robot; On the other
hand, an automatic robot will involve the
use of a digital computer such as the
Programmable Logic Controller (PLC) for
the purpose.
3.1 PRODUCT DESIGN &
SPECIFICATIONS.
The engineering requirements are further
comprehended to generate a list of product design
specifications which are concluded in Table 2.3.1.
Table 2.3.1: Product Design Specifications of the
stair-climber
1. Functional Performance:
I. Movement:
A. The movement of the robot on the stairs is based on the drag and reaction forces acting on the body.
B. The movement of the robot will be stable and
consistent.
C. The safety factor is assigned to be 2.
II. Power source:
A. DC High Torque Gear motor with working voltage
of 12V will be selected.
B. A battery with regular voltage capacity 12V is
used to give a required current to the motor.
III. Material selection:
A. The solid base will be manufactured with less
weight material such as Wood.
B. The shafting materials will be manufactured
with stainless steel.
2. Physical Requirements:
I. Size:
A. The outermost dimensions of the stair-climber will be less than width: 40cm; length: 72cm.
B. The size of the stair-climber will not affect its
movements.
II. Weight:
A. As suggested by our supervisor, the total
weight of the robot must not exist 25kg such that the
mechanical motion drivers will not be overloaded easily.
B. The centre of mass of the stair-climber will be
designed to locate in the front region, probably 32.5cm from
the centre position of the robot, so that the robot can stay close
to the higher steps to facilitate proper and safe movement.
3.3 DETAILED DESIGN
In this chapter, the final design of the
stair-climber will be discussed. The working
principle of the stair-climber is illustrated with
the breakdown of the design structure. The
required torque driven by the motor is computed,
while experiments are performed to test for the
functionality of the motor.
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Figure 3.3 In the present work we have designed
the robot parts and assembled the parts using
Solid works.
Figure 3.3.1 Assembly view of our robot.
Our group believes that a simple design
similar to this stair-climber can be capable of
satisfying all the requirements as mentioned in the
project statements.
3.3.1. STRUCTURE OF THE DESIGN
The stair-climber consists of numerous
components. All of them have their own specific
use. Only the proper assembly can result in their
smooth motions.
The final design of the robotic climber
installs one motor, one battery, six gears, ten
bearings, five stainless steel shafts, four wood
wheels, and two aluminum body frame. The motor
is responsible for the linear propulsion and
responsible for the moving up or down and left or
right motion of the robot
The robot can be commonly divided into
two major parts. One is the base part and another
one is gear part. For the former part, most of the
components are mounted on the base plate. It is
because the base plate is made of the aluminum,
which can provide a support and even withstand
the impact when the climber moves up or down. In
the final design, the forward or backward motions
are mainly depended on the wheels. There are four
wheels, 2 front wheels and 2 rear wheels. The front
wheels are responsible for driving the robot and the rear wheels are responsible for supporting the robot
when it lifts up. The wheels are connected onto the
19 mm shaft. The bearings are installed on the
sides of both aluminum bases, to maintain the
wheels alignment correctly and rotate with ease.
For the gear part, the elevation of the
robot is mainly relied on the gear; the rotational
force generated by the motor is transmitted by the
17 teeth pinion gear to the aluminum gear. With the
assistance of the front wheels, the robot can
transform its motion from standing to moving.
There are two sprockets mounted on the wheel
shafts. Their function is to connect the front and
rear wheels and to rotate them at equal speed.
Figure 3.3.1.1 Design model of wheel.
Figure 3.3.1.2 Design model of pinion gear.
Figure 3.3.1.3 Design model of body frame.
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Figure 3.3.1.4 Design model of chain and
sprocket.
Figure 3.3.1.5 Overall view of our robot.
4.0. WORKING PRINCIPLE Our team makes use of a simple
mechanical design to fulfill the requirements of
climbing up, down or right, left of the stairs.
Simplifying the working mechanisms, there must
be an upward and forward displacement for the
robot when it is climbing upstairs, while a
downward and backward displacement when
downstairs.
4.1. CLIMBING UPSTAIRS
When the robot is switched on, the battery
gives the required current to the motor (i.e., 1.2-2.0
amps) and the motor gets rotated and it transmits
the rotational force the pinion gear of 17 teeth and
from the pinion it gets transferred to the aluminum
gear of 41 teeth and then by series transmission, it
reaches the final gear which is attached to the front
wheel shaft. Now the front wheel rotates and by the
chain drive mechanism, the rear wheels also rotated
and thus the motion of the robot it done.
The stair-climber can travel in a straight
line and it will stop when the front wheel touches
the first step of the stairs. Then the front wheel
design gets lock with the stairs, and it pulls the
robot to climb up. Then with the help of sprockets
and chains the rear wheel also climbs the stairs.
Thus, our robot climbs the stairs with
simple mechanism.
Figure 4.1.1 lifting the robot.
4.2 MOTOR SELECTION
4.2.1. REQUIREMENTS
Before selecting an adequate motor for the
robot, some assumptions are made and listed as
follow:
1) The total weight of the robotic
climber is about 25 kg.
2) The safety factor is 2. 3) The efficiency of selected motor
nearly attains 85%.
4) The friction between the gears is
negligible.
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4.2.2. STAIR WHEEL DESIGN
The Universal stairs are designed
based on the height and width, which is called
as rise and run.
Height of the stair = Rise of the stair =11inch
= 27.94 cm.
Width of the stair = Run of the stair = 7.5inch
= 19.05 cm.
Radius of the stair wheel = {(a2 + b2)/ 3}
= {(19.052 + 27.942)/ 3
= {(362.9025 + 780.6364)/ 3}
= (1143.54/3)
= 381.18
= 19.52 20
Radius of the stair wheel = 20 cm.
4.2.3. TORQUE CALCULATION
When the body is initially at rest,
only body weight acts on the slope.
Figure 4.2.3.1: The SLOPE DIAGRAM of the
body.
mgx = Mg*sin() -(1)
mgy = Mg*cos() -(2)
To hold the body in steady
condition, frictional force (f) must act between the
body and the slope.
Figure 4.2.3.2: The forces acting on the body which
is placed on the slope inclined to a certain angle
Torque= Force*Radius. - (3)
When the Robot moves on the
slope, there will be acceleration acting on the body
and there will be a radial force displacement.
To balance the force on X- direction.
fx = M*a = f-mgx -(4)
Inserting the equation of the Torque equation and
mgx from (3) and (1) respectively;
M*a = (T/R) - M*g*sin ()
T = R* (M*a) + (M*g*sin)
T = R* M (a + g*sin) - (5)
NOTE:
Acceleration, (a) = (Final Velocity - Initial
Velocity) / Time.
Where,
Final Velocity = 0.5 m/s.
Initial Velocity = 0 m/s.
Time Taken = 1 sec
(a) = (0.5 - 0)/ 1
Acceleration, (a) = 0.5 m/s2.
Equation (5) represents the total Torque
required to accelerate the robot up and incline. In
order to arrive a Torque needed for each drive
motor, divide the total Torque by number of drive
wheels.
T = R* M (a + g*sin) - (6) N
Considering the efficiency of the motor, gearing
and wheel (slip);
T = R*M (a + g*sin)*(100) - (7)
N*(e)
Considering the factor of safety, as 2;
T = R*M (a + g*sin)*(100)*2 - (8)
N*(e)
= (0.2)*25(0.5 + 9.81*sin36)*(100)*2
4*(85)
= 18.43 19
T = 19 Nm.
-(6)
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Hence the torque of the motor must be greater
than the calculated torque (i.e.,) the torque of
the motor should be T > 19 Nm.
Power = Torque* - (9)
= {19*(2 N)}/ 60
P = 596.90 watts.
The power of the motor should be more than 600
watts.
5. GEAR CACULATION
5.1. SPEED OF GEARS
Our motor speed is 300 rpm. So this
becomes the initial speed. (N1= 300 rpm.)
Our motor has high torque (i.e., 30Nm) so
wheel speed will be low. Our required wheel speed is 10 rpm.
5.2. TEETH CALCULATION
According to “Design of Transmission
System” a gear must have minimum 17-25 teeth.
So we consider our pinion gear having 17 teeth.
We decided to have a velocity ratio as 3.
Therefore, by the velocity ratio formula; Z2 = 17*3 = 51 Teeth. Hence the No. of teeth on
driven gear is 51 teeth.
Fig-5.2.1 COMPOUND GEAR DIAGRAM
Compound gears are used in engines,
workshop machines and in many other mechanical devices. Sometimes compound gears are used so
that the final gear in a gear train rotates at the
correct speed. So we used compound gears to
reduce the motor speed to the required output
speed. In our project, gear ‘B’, gear 'D' are actually
two gears attached to each other and they rotate
around the same center.
By Speed Ratio Formula;
The speed ratio is given by
relating the speed and the number of gears. The
compound gears have the teeth as Gear A = Gear C
= Gear E = Z1= 17 Teeth, and
Gear B = Gear D = Gear F = Z2= 51 Teeth. The
pinion gear rotates with the speed of motor, so the
initial speed is 300rpm.
Driven = 51 => 3
Driving 17
Since Gear A rotates at 300rev/min, the
rotational speed of gear B will be obtained by
DIVIDING it by 3. Thus, Gear B moves at 300/3 =
100 rev/min.
As the Gear B rotates at the speed of 100rev/min, the Gear C also rotates at the
same speed of Gear B, since they are attached to
the same shaft. Now, the speed of the Gear C is
100rev/min.
Driven = 51 => 3
Driving 17
Since Gear C rotates at 100rev/min, the
rotational speed of gear D will be obtained by
DIVIDING it by 3. Thus, Gear D moves at 100/3 =
33.3 33rev/min.
As the Gear D rotates at the speed of
33rev/min, the Gear E also rotates at the same
speed of Gear D, since they are attached to the
same shaft. Now, the speed of the Gear E is
100rev/min.
Driven = 51 => 3
Driving 17
Since Gear E rotates at 33rev/min, the rotational speed of gear F will be obtained by
DIVIDING it by 3. Thus, Gear F moves at 33/3 =
11rev/min
As the Gear D rotates at the speed of
11rev/min, the wheel also rotates at the same speed
of Gear D, since they are attached to the same
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shaft. Now, the speed of the wheel is 100rev/min,
which is the required speed.
This is the reason for using 3 driving gears and
3 driven gears; totally = 6 gears.
5.3. PITCH CIRCLE DIAMETER
(PCD) CALCULATION
Module (m) = Pitch Circle Diameter
Number of teeth on gear
1) No. of teeth in driving gear (Z1) = 17 Teeth.
2 = Pitch Circle Diameter
17
Pitch Circle Diameter for Driving Gear =34mm.
2) No of Teeth on driven gear (Z2) = 51 Teeth.
2 = Pitch Circle Diameter
51
Pitch Circle Diameter for Driven Gear =102mm.
6.0 ARDUNIO PROGRAMMING:
Here we use an Arduino board to control
the speed of the motor. The programming is done
and it is installed into the Arduino board. It is then connected to the robot through connecting wires.
We also use the Bluetooth control device to switch
on and off the robot which is connected along with
the Arduino board, this is controlled using the
application stored in the cell phone.
Figure 6.0.1: Arduino and Bluetooth device
6.1: EVALUATING RESULT:
Figure 6.1.1: Robot circuit connection.
Figure 6.1.2: Robot in initial position.
Figure 6.1.: Robot in climbing position.
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6.2 ADVANTAGES:
Simple mechanical design.
Stable.
Simple gear arrangement.
Universal stairs to climb.
It can be controlled by smart phone.
7.0 CONCLUSION AND FUTURE
SCOPE:
The robot is called stair-climbing robot
from the fact that it's designed to cope with stairs, very rough terrain, and is able to move fast on flat
ground. To sum up, the main concern of this paper
is to design a rescue robot that is capable to go into
slightly destroyed areas to find and help rescue
people. Arduino is used in this robot in order to
control the direction (right, left, forward and
reverse) using one DC gear motor in sides of the
robot. Also Arduino is used to control the motion
of camera using stepper motor and the motion of
servo motor which is used to let the robot climb
and go down the stairs. Arduino is the brain of
stair-climbing robot. The overall system worked successfully. Firstly we tested our robot using
ordinary manual switch (wired system).Then RF
module (transmitter and receiver) is used in order
to make the system wireless by using mobile
phone control. The control used was by making
interface between Arduino and visual basic in both
directions; sending data from mobile phone to
robot or vice versa. Overall benefits of rescue
robots to these operations include reduced
personnel requirements, reduced fatigue, and
access to unreachable areas.
7.0.1 FUTURE SCOPE: DETECTING BOMBS
• Our idea is saving the life of bomb squad
and people from bomb explosions that takes place in buildings, schools, temples
and other public areas.
• So we have decided to design a staircase robot. Since we can't get the sensors
which is used to detect bombs due to the
reason that the security forces are not
providing us. So we decided to take that
process on Future development, (i.e.,)
“Deduct Bombs in Buildings.”
DIFFUSING BOMBS: Our team has
decided to take our project into the next level, (i.e.,)
initially we decided to do a project on detecting
bombs, and then to take this project for diffusing it
by using Grippers and Robotic Arms.
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time sensory control system for intelligent security robot”
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a tiny mobile robot platform for large-scale ad-hoc sensor
networks”, IEEE International Conference on Robotics
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platform for distributed robotics”, IEEE/RSJ International
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